Method of making nonwoven sheet materials, tapes

ABSTRACT

Nonwoven sheet materials, and pressure sensitive adhesive tapes formed from nonwoven sheet materials are provided. The nonwoven sheet materials comprise a randomly interlaced fibrous web of tensilized nonfracturable staple fibers and binder fibers, wherein the fibrous web is pattern embossed, and is interbonded by a chemical bonding agent, physical entanglement, or a combination thereof, and further wherein the nonwoven sheet material is readily finger-tearable in the cross web direction. Methods of making nonwoven sheet materials and adhesive tapes are also provided.

This is a continuation of application Ser. No. 08/442,159 filed May 16,1995, now abandoned which is a continuation-in-part of application U.S.Ser. No. 08/114,376 filed Aug. 30, 1993, ABN which is acontinuation-in-part of U.S. Ser. No. 07/830,063 filed Feb. 3, 1992 ABN.

FIELD OF THE INVENTION

The present invention relates to nonwoven sheet materials, and tapesmade therefrom, and in particular, to improved nonwoven sheet materialsand tapes that exhibit enhanced tear characteristics, wet and drystrength, and good Hand values.

BACKGROUND OF THE INVENTION

Nonwoven sheet materials are often used as the backing or web componentof tapes and the like. These tapes are commonly used in the health-careindustry for affixation of a variety of articles, such as dressings andtubings, and as backings and affixation materials for pre-madedressings, such as first-aid dressings and island-type dressings. Theyare also commonly used as affixation materials on certain types ofproducts, such as diagnostic electrodes, surgical grounding plates, andmonitoring electrodes.

Tapes formed from nonwoven sheet materials fall into two generalcategories based on performance needs. Category I includes sheetmaterials, and tapes made therefrom, that can be torn in the crossmachine or cross web direction. However, these materials often cannot betorn cleanly, and therefore, display uneven or irregular torn edges. Onthe other hand, category II includes those sheet materials and tapesthat, for practical purposes, cannot be torn in either the machine orweb direction or the cross web direction.

In general, category I nonwoven materials are predominantly comprised ofcellulosic fibers, and exhibit a web direction to cross web directiontensile strength ratio of less than 2.5 to 1. Cellulosic fibers areinherently fracturable (i.e., are easily broken under stress), asopposed to many synthetic, polymeric fibers, that are essentiallynonfracturable.

The cellulosic fibers used in category I sheet materials are typicallybonded together by a chemical binder that immobilizes, or partiallyimmobilizes the fibers. In addition, the chemical binder increases thedensity of the sheet materials, and provides other advantageousproperties, such as enhanced tensile strength, elongation at break, Hand(i.e., conformability), fuzzing, and the specific tear characteristicsnoted above. However, these advantageous properties are rapidlycompromised when the sheet material becomes wet, and especially when itbecomes saturated with water or other water-based fluids.

Category II materials are most frequently formed from essentiallynonfracturable synthetic fibers, and are either thermally, mechanically,or chemically bonded to provide structural integrity to the sheetmaterials. These materials can display enhanced tensile strength,elongation, Hand, and fuzz formation depending on their particularconstruction. For example, mechanically bonded category II materials aretypically softer and more fuzzy, in comparison with the chemicallybonded materials, that tend to be stiffer and less fuzzy. However, invirtually all instances, category II sheet materials are essentiallyincapable of being torn in the cross web direction, and thus, do notmeet the affixation requirements of the health-care industry.

Both category I and II nonwoven sheet materials and tapes enjoyreasonably extensive use in the wound treatment and medical deviceaffixation areas of the practice of health-care. However, neither typeof material has been able to make significant advances into the broaderareas of the health-care market due to their inherent limitations.

Category I materials lack water resistance, and are unable to providesufficient strength, while still maintaining softness, Hand and/orreasonable tear characteristics. Strength can be improved by changingthe web direction to cross web direction orientation ratios of thefibers at the expense of tear. In addition, strength can also beimproved by increasing the basic fiber content and weight at the expenseof Hand and tear.

Altering the characteristics of category II sheet materials made withsynthetic polymer fibers is even more restrictive. Reasonably good tearcan only be achieved by utilizing fibers that make the sheet materials,and resulting tapes, very stiff. In so doing, the fiber-to-fiber bondsare essentially locked-up, thereby reducing fabric conformability, andproviding a tear which is extremely difficult, and not satisfactory interms of ragged edges and failure to tear straight.

Many attempts have been made in recent years to enhance thecharacteristics of category I and II materials, or to provide nonwovensheet materials and tapes with the desirable characteristics of bothcategory I and II materials. In so doing, different fiber types,contents, and weights of the nonwoven sheet materials have been tried.In addition, various bonding techniques, including bonding with achemical sizing agent, physical entanglement of the web (e.g.,hydroentanglement) and thermal bonding, such as through thermalembossing, have been employed. See, e.g., U.S. Pat. No. 4,973,513(chemical bonding with LAB), U.S. Pat. No. 4,341,213 (chemical bondingto increase strength and flammability), U.S. Pat. No. 4,772,499(hydroentanglement and partial chemical bonding), U.S. Pat. No.3,737,368, and U.S. Pat. No. 3,507,943 (thermal embossing with engravedrollers).

For example, U.S. Pat. No. 3,121,021 discloses surgical adhesive tapeformed from a tissue backing of rayon staple fibers coated with anon-tacky hydrophobic rubbery fiber-sizing polymer. The polymer-bondedbacking is coated with a thin layer of pressure-sensitive adhesive thatexhibits a microporous structure after drying. Incorporation of thehydrophobic rubbery fiber-sizing polymer serves to increase the waterrepellency, and thus, the wet strength of this category I material.Similarly, U.S. Pat. No. 4,112,177 provides essentially the samenonwoven backing as with U.S. Pat. No. 3,121,021, however, multipleadhesive layers are applied to the backing to improve the overalladhesive properties of the tapes formed therefrom. A further example ofa porous, double-coated adhesive tape is disclosed in U.S. Pat. No.4,844,973.

U.S. Pat. No. 4,292,360 discloses a multi-ply nonwoven sheet materialthat can be used to make pressure-sensitive adhesive tapes. The sheetmaterials are comprised of two nonwoven webs that are overlaid andbonded together by a rewettable chemical binder. The nonwoven webs canbe formed of any type or combination of staple fibers, either alone, orin combination with binder fibers. In addition to the chemical binder,the sheet materials can also be optionally calendered or embossed.

U.S. Pat. No. 3,908,650 discloses a microporous tape formed from anonwoven web coated on one side with a porous layer of apressure-sensitive adhesive, and on the other with a porousthermoplastic film. The fibers adjacent the thermoplastic layer are, atleast to some extent, water repellent. Optionally, the fibrous web maybe thermally bonded or chemically bonded with a sizing agent.Utilization of the thermoplastic layer imparts increased abrasion andsoil resistance to the overall tape.

U.S. Pat. No. 4,772,499 discloses a nonwoven web that is readilytearable in the cross web direction. The tearability of the web isenhanced by pattern bonding portions of the web with a bonding agent.After drying, the web is stated to be readily tearable in the cross webdirection along the non-bonded portions of the web. Also, U.S. Pat. No.4,303,724 discloses the use of texturized or false twist yarns in thefiling of nonwoven fabrics to improve their tear characteristics.

West German Patent No. DE 1 595 300 discloses nonwoven fabrics formedfrom wet-laid webs that are hot calendered while the web still retainsfrom 10% to 40% by weight residual moisture. These webs are comprised ofunstretched polyester binder fibers, and optionally can includestretched polyester fibers, polyacrylamide fibers, and/or polyamideimide fibers. Further examples of thermal bonding as the principal meansof reinforcing nonwoven materials can also be found in U.S. Pat. Nos.4,731,277, 4,639,390, 4,511,615, 4,490,427, and 4,083,913. In addition,thermal bonding can be brought about by embossing such sheet materialsusing heated, engraved rollers. See, e.g., U.S. Pat. Nos. 3,737,368 and3,507,943.

U.S. Pat. No. 4,490,425 discloses a soft and fluffy nonwoven fabricformed by thermal bonding staple fibers, endless fibers, or both, andneedle puncturing (i.e., tacking) one or both sides of the fabric toform the fluffy surface. Thereafter, one or more of the sides are coatedwith a thermal adhesive to yield a fabric useable as an interlining invarious garments. Similar interlining materials and methods of theirpreparation are also disclosed in U.S. Pat. Nos. 4,451,314 and4,148,958.

None of the previously described fabrics or tapes has successfullycombined the advantages of category I and II materials, whileeliminating their shortcomings. In fact, to date, no single nonwovensheet material, or tape made therefrom, exhibits enhanced dry strength,comparable wet strength, and ease of tear in the cross web direction,while maintaining reasonable Hand values.

SUMMARY OF THE INVENTION

The present invention provides nonwoven sheet materials, and tapesformed therefrom, made with tensilized nonfracturable staple fibers andbinder fibers, and formed from a combination of interbonding and patternembossing techniques. These sheet materials are especially useful astape backing fabrics that are finger tearable in the cross web directionwithin the requirements of the user community, and also possess a numberof other desirable properties, including enhanced dry strength,comparable wet strength, low Hand measurements, and a web directiontensile strength to cross machine direction tensile strength ratio ofpreferably less than 3:1.

In particular, the present invention provides a nonwoven sheet materialcomprising a randomly interlaced fibrous web of tensilizednonfracturable staple fibers and binder fibers, wherein the fibrous webis pattern embossed, and is interbonded by a chemical bonding agent,physical entanglement, or a combination thereof, and further wherein thenonwoven sheet material exhibits a Hand measurement of less than 250grams for about a 20 cm square sheet, and is readily finger-tearable inthe cross web direction. In a preferred embodiment, the nonwoven sheetmaterial is also readily finger tearable in the cross web direction.Further in a preferred embodiment the nonwoven sheet material is singleply.

Also, the present invention can provide a pressure-sensitive adhesivetape comprising a nonwoven backing with first and second surfaces, thenonwoven backing having a pressure-sensitive adhesive coated on thefirst surface, wherein the nonwoven backing comprises tensilizednonfracturable staple fibers and binder fibers randomly interlacedtogether to form a fibrous web, the fibrous web being pattern embossed,and interbonded by a chemical bonding agent, physical entanglement, orcombinations thereof, and further wherein the adhesive tape exhibits aHand measurement of less than 250 grams for about a 20 cm square sheet,and is readily finger-tearable in the cross-web direction. Preferably,the fibrous web is single ply.

Further, the present invention can provide a method of making a nonwovensheet material comprising: (a) forming a randomly interlaced fibrous webof tensilized nonfracturable staple fibers and binder fibers; (b)pattern embossing the fibrous web; and (c) interbonding the fibrous webusing a chemical bonding agent, physical entanglement, or a combinationthereof, to form a nonwoven sheet material, wherein the nonwoven sheetmaterial exhibits a Hand measurement of less than 250 grams for about a20 cm square sheet, and is readily finger-tearable in the cross webdirection.

These and various other advantages and features of novelty whichcharacterize the invention are pointed out with particularity in theclaims annexed hereto and forming a part hereof. However, for a betterunderstanding of the invention, its advantages, and objects obtained byits use, reference should be had to the accompanying descriptive matter,in which there is illustrated and described preferred embodiments of theinvention.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

Nonwoven Sheet Materials

The fibrous web component of the nonwoven sheet materials and tapesaccording to the present invention is made in accordance withconventional methods known in the art, including wet-laid methods,dry-laid methods, such as air layering and carding, and direct-laidmethods, such as spunbonding and meltblowing. Examples of such methodsare disclosed in U.S. Pat. No. 3,121,021 to Copeland, and U.S. Pat. No.3,575,782 to Hansen, the disclosures of which are herein incorporated byreference.

Both tensilized nonfracturable staple fibers and binder fibers are usedin the formation of the fibrous web component of the nonwoven sheetmaterials and tapes of the present invention. As used herein,"tensilized nonfracturable staple fibers" refer to staple fibers, formedfrom synthetic polymers, that are drawn during manufacture, such thatthe polymer chains substantially orient in the machine direction or webdirection of the fiber, and that will not readily fracture whensubjected to a moderate breaking force. The controlled orientation ofthese staple fibers imparts a high degree of ordered crystallinity (e.g.generally above about 45% crystallinity) to the polymer chainscomprising the fibers. Generally, the tensilized nonfracturable staplefibers of the present invention will not fracture unless subjected to abreaking force of at least 3.5 g/denier. The terms "machine direction"and "web direction" are used interchangeably and refer to the lengthwisedirection of the web. The fibers which comprise the nonwoven sheetmaterials orient in the web direction of the nonwoven sheet materials.The terms "cross machine direction" and "cross web direction" are usedinterchangeably herein and refer to a direction about perpendicular tothe web direction of the nonwoven sheet materials.

Nonlimiting examples of suitable tensilized nonfracturable staple fibersaccording to the present invention include polyester staple fibers,polyolefin staple fibers, polyamide staple fibers, polyacrylate staplefibers, polycarbonate staple fibers, polysulfone staple fibers, orcombinations thereof.

Preferably, the tensilized nonfracturable staple fibers compriseoriented polyolefin staple fibers, such as oriented polyethylene,polypropylene, or polybutylene staple fibers, oriented polyester staplefibers, such as polyethylene terephthalate (PET), or combinationsthereof. These oriented staple fibers are preferably from about 1 cm toabout 10 cm, more preferably, 2 cm to 5 cm in length, and display afineness of from about 0.1 denier to about 20 denier, more preferablyfrom about 0.5 denier to about 5 denier, and most preferably from about0.7 denier to about 2 denier.

In a particularly preferred embodiment, the tensilized nonfracturablestaple fibers comprise oriented polyester staple fibers, such as 0.75denier polyester staple fibers (type L-30, polyethylene terephthalate(PET); Eastman Chemical Products, Inc., Kingsport, Tenn.; or, standardpolyester staple fibers (PET); Hoechst Celanese, Charlotte, N.C.), 1.25denier polyester staple fibers (Style T-131, PET; Hoechst CelaneseCorp., Charlotte, N.C.), and/or 2.0 denier standard polyester staplefibers (PET) (Hoechst Celanese Corp., Charlotte, N.C.).

Any type or types of binder fibers can be employed to form the fibrousweb of the present invention, as long as they are capable ofmelt-bonding to the tensilized nonfracturable staple fibers of thefibrous web without fracturing, or substantially weakening thetensilized nonfracturable staple fibers. In this regard, it ispreferable that the binder fibers be formed from one or more man-madethermoplastic polymers that are capable of melt-bonding with thetensilized nonfracturable staple fibers used in the nonwoven sheetmaterials and tapes of the present invention. Furthermore, the binderfibers can comprise a wide variety of binder fiber configurations thatare well known in the art, including, without limitation, totallymeltable binder fibers, side-by-side binder fibers, bicomponent binderfibers, elliptical core-sheath binder fibers, concentric core-sheathbinder fibers, or combinations thereof.

Examples of suitable binder fibers, include, without limitation,polyester binder fibers, polyolefin binder fibers, such as thermoplasticpolyethylene, polypropylene, and polybutylene binder fibers, polyamidebinder fibers, or combinations thereof. These binder fibers arepreferably from about 1 cm to about 20 cm, more preferably, 2 cm to 10cm in length, and display a fineness of from about 0.1 denier to about20 denier, more preferably from about 0.2 denier to about 10 denier, andmost preferably from about 0.5 denier to about 6 denier.

In a particularly preferred embodiment, the binder fibers comprisecore-sheath binder fibers containing, for example, an oriented polyesteror polyolefin fiber core surrounded by an outer sheath of a meltablepolyester or polyolefin resin. Specific examples of suitable core-sheathbinder fibers for use in the fibrous webs of the present inventioninclude Diawa™ binder fibers (1.5 denier, 38 mm, crystallinepolypropylene core and meltable polyethylene sheath; Chori America,Inc., Los Angeles, Calif.); Melty™ binder fiber (2 denier, 38 mm,oriented polyester core and meltable polyester sheath; Chori America,Inc.); K-52 binder fibers (2 denier, 38 mm, oriented polyester core andmeltable polyester sheath; Hoechst Celanese Corp., Charlotte, N.C.); andK-54 binder fibers (2 denier, 38 mm, oriented polyester core andmeltable polyester sheath; Hoechst Celanese Corp., Charlotte, N.C.).

The weight ratio of tensilized nonfracturable staple fibers to binderfibers in the fibrous web will depend upon the application to which thenonwoven sheet materials or tapes of the present invention are to beput. In most cases, predetermined strength, tearability, and otherrequirements of the nonwoven sheet materials and tapes of the presentinvention can be obtained by balancing the quantity of high-strength,tensilized nonfracturable staple fibers against the quantity ofthermoplastic binder fibers needed to insure adequate binding, andultimately, the structural integrity of the fibrous web.

Generally, from about 95% to about 50%, preferably from about 90% toabout 60% by weight of the fibrous web will be comprised of one or morevarieties of tensilized nonfracturable staple fibers, while from about50% to about 5%, preferably from about 40% to about 10% by weight of thefibrous web will be binder fibers. In a preferred aspect, the weightratio of tensilized nonfracturable staple fibers to binder fibers willbe from about 10:1 to about 1:10, more preferably from about 5:1 toabout 1:1, and most preferably from about 4:1 to about 2:1.

The thickness of the fibrous web which forms the major component of thenonwoven sheet materials according to the present invention is largelydependent upon the desired use. In general, the fibrous web can be fromabout 0.04 mm to about 0.5 mm in thickness. When the desired end use ofthe nonwoven sheet material is as a backing for medical tape, it ispreferred that the fibrous web have a thickness of from about 0.15 mm toabout 0.4 mm. In addition, the weight of the fibrous web can be fromabout 10 g/m² to about 100 g/m², preferably from about 15 g/m² to about70 g/m², and more preferably from about 20 g/m² to about 50 g/m².

In accordance with the principles of the present invention, the fibrousweb is interbonded with a chemical bonding agent, through physicalentanglement, or both, and is pattern embossed to yield the nonwovensheet materials of the present invention. In practice, it is importantthat the sequence of interbonding and pattern embossing steps applied tothe fibrous web be carried-out in a certain order. The application of achemical binding agent to the fibrous web should be the last step in thetreatment of the web, and when utilized, interbonding by physicalentanglement should be the first step. For example, in one embodiment,the fibrous web is first physically entangled, then pattern embossed,and finally saturated with a chemical binding agent, to yield a nonwovensheet material according to the present invention.

One method of interbonding the fibrous web is to physically entangle thefibers after formation of the web by conventional means well known inthat art. For example, the fibrous web can be needle-tacked as shown inU.S. Pat. No. 5,016,331, the disclosure of which is herein incorporatedby reference. In an alternative, and preferred method, the fibrous webcan be hydroentangled, such as described in U.S. Pat. No. 3,485,706, thedisclosure of which is herein incorporated by reference. One such methodof hydroentangling involves passing a fibrous web layered betweenstainless steel mesh screens (e.g., 100 mesh screen, National WireFabric, Star City, Ark.) at a predetermined rate (e.g., about 23 m/min)through high pressure water jets (e.g., from about 3 MPa to about 10MPa), that impinge upon both sides of the web. Thereafter, thehydroentangled webs are dried, and can be subjected to pattern embossingand chemical binder saturation, as described herein.

All of the nonwoven sheet materials according to the present inventionare pattern embossed, according to procedures well known in the art,such as those described in U.S. Pat. Nos. 2,464,301, 3,507,943, and3,737,368, the disclosures of which are herein incorporated byreference. In general, the fibrous web is passed through a metal rollthat is patterned (e.g., engraved) with raised and depressed areas, anda solid back-up roll, generally formed of metal or rubber. However, thefibrous web can also be fed between two patterned rolls displayingcorresponding or alternating engraved areas. In either case, it istypical to supply heat to one or more of the rolls so that the fibrousweb is thermally bonded along the points of pattern contact.

In a preferred embodiment, the fibrous webs according to the presentinvention are thermally embossed with a pattern roll and a solid back-uproll. During embossing, it is important to closely control thetemperature of the pattern roll. In general, the temperature must besuch that the tensilized nonfracturable staple fibers and binder fibersare thermally fused at the points of contact without fracturing thestaple fibers, or seriously weakening the fibrous web below a useablestrength level. In this regard, it preferred to maintain the temperatureof the pattern roll between about 120° C. and 180° C., more preferablybetween about 125° C. and 145° C. In addition, the pattern roll shouldcontact the nonwoven sheet material at a pressure of from about 0.10 MPato about 0.30 MPa, more preferably from about 0.15 MPa to about 0.25MPa.

The particular pattern engraved on the embossing roll will depend uponthe intended use for the resulting nonwoven sheet materials and tapes.However, with standard medical tapes, it is preferable to use either alinear pattern that thermally embosses a series of lines along the crossweb direction of the sheet material/tape backing, or a cross-hatch(i.e., square) pattern, that results in a series of intersectingembossed lines running in both the web direction and cross web directionon the sheet material/tape backing. In a preferred embodiment, thecross-hatch pattern is comprised of a series of squares formed fromembossed lines of about 0.01 mm to about 0.05 mm in width, separatedfrom each other by a square-shaped, un-embossed area of from about 0.05mm to about 0.1 mm on each side.

The embossed surface area of the nonwoven sheet materials shouldcomprise no more than about 95%, preferably less than about 80%, morepreferably less than about 50%, and most preferably less than about 30%of the total surface area of the fibrous web. However, in no instanceshould 100% of the surface area of the fibrous web be thermally embossed(i.e. hot calendered). In preferred embodiments of the presentinvention, a linear, cross web direction embossed pattern preferablyresults in an embossed area of from about 10% to about 20%, while asquare, cross-hatch pattern results in about a 25% to 35% embossed area.

A wide variety of chemical binding agents can be applied to the fibrouswebs of the present invention by art-recognized processes. Nonlimitingexamples of useful chemical binding agents include acrylics, vinylacrylics, acetate/ethylene, polyvinyl acetate, and the like. Whateverchemical binder is employed, it should have an affinity for, and readilybind with, the tensilized nonfracturable staple fibers and/or binderfibers comprising the fibrous web.

It is preferable that the chemical binding agent comprise a water-basedchemical binder, including, without limitation, latexes incorporatingacrylics, styrene/butadiene rubbers, vinyl acetate/ethylenes, vinylacetate/acrylates, polyvinyl chloride, polyvinyl alcohols,polyurethanes, vinyl acetates, acrylic/vinyl acetate, and the like.These water-based chemical binders are typically applied to the fibrousweb at about 25% to about 35% solids, using any suitable coating method,including, wire-wound rod, reverse roll, air knife, direct and offsetgravure, trailing blade, print bond, foam, and spray coating methods.

Specific examples of preferred chemical binding agents according to thepresent invention, include, without limitation, Rhoplex™ E-2559 (anapproximately 45% solids acrylic latex binder; Rohm & Haas Co.,Philadelphia, Pa.), UNOCAL™ type 76-4402 (an approximately 50% solidsstyrene/butadiene rubber latex; UNOCAL Corp., Charlotte, N.C.), andNational Starch™ No. 78-6283 (an approximately 45% solids acrylic/vinylacetate copolymer latex; National Starch Corp., Bridgewater, N.J.), withNational Starch™ No. 78-6283 being particularly preferred.

The chemical binding agent is applied in amounts sufficient to providethe desirable properties, such as dry strength, wet strength, and tearproperties, demonstrated by the nonwoven sheet materials and tapes ofthe present invention. However, the amount of chemical binding agentemployed can be varied depending upon the intended use. For example,more chemical binding agent may be applied to increase the strength ofthe nonwoven sheet materials, while less binder may be used to lower theHand (i.e., improve conformability) of the materials.

In general, when the fibrous web is saturated with a chemical bindingagent to form the nonwoven sheet materials and tapes of the presentinvention, the weight of the chemical binding agent in the fibrous web,after being dried, is from about 10 g/m² to about 40 g/m², preferablyfrom about 15 g/m² to about 30 g/m². In this regard, it is preferredthat the weight ratio of the fibers comprising the fibrous web to thechemical binding agent incorporated in the fibrous web be from about 5:1to about 1:5, more preferably from about 3:1 to about 1:3, and mostpreferably from about 2:1 to 1:2.

The fibrous web according to the present invention can also optionallyincorporate a water-based release coating, such as a low-adhesionbacksize (LAB), at essentially the same time as, or after incorporationof, the chemical binding agent into the web. Preferred useable LAB'scomprise those listed in, and applied by the methods described in, U.S.Pat. No. 4,973,513, the disclosure of which is herein incorporated byreference. After the chemical binding agent, and optional LAB, isapplied, the fibrous web is dried using any appropriate drying means,such as contact drying, circulating air ovens, impingement ovens,through-air ovens, and the like.

Presently, there are two particularly preferred general constructions ofnonwoven sheet materials in accordance with the present invention. In afirst embodiment, the preferred nonwoven sheet material comprises afibrous web of about 80% by weight of about a 1 denier, 4 cm length,oriented polyester staple fiber combined with about 20% by weight ofabout a 2 denier, 5 cm length, polyester binder fiber, having an averagetotal fiber weight of about 20 g/m². This fibrous web is patternembossed with a square, cross-hatch pattern that results in about 28%bonded surface area. Thereafter, the embossed fibrous web is saturatedwith a water-based acrylic copolymer chemical binding agent, diluted toabout 28% solids, and dried to a binder weight of about 15 g/m², toyield nonwoven sheet materials according to the present invention.

The second preferred nonwoven sheet material comprises essentially thesame material as the first embodiment, except that the fibrous web ishydroentangled prior to being pattern embossed, and the total fiberweight is increased to about 50 g/m², while the binder weight isincreased to about 25 g/m². Thus, the ratio of total fiber weight tobinder weight is approximately 2:1 versus essentially 1:1 for the firstpreferred embodiment.

Tapes

After the fibrous web has been interbonded and pattern embossed to formthe nonwoven sheet materials of the present invention, the sheetmaterials may be wound in a roll for transportation, and laterapplication of an adhesive, or other appropriate coatings used to formstandard medical tapes and the like. Alternatively, the nonwoven sheetmaterial may be conveyed directly to an adhesive coater, followed byslitting into individual tape rolls.

Preferably, the nonwoven sheet materials are coated with a layer ofpressure-sensitive adhesive to form the tapes according to the presentinvention. In this regard, the pressure-sensitive adhesive that isapplied to the nonwoven sheet materials may be solvent-based,water-based, or a hot-melt adhesive. Suitable adhesives, and theirmethods of application, are described, for example, in U.S. Pat. No.2,708,192 (phenolic cured rubber based adhesives), U.S. Pat. No. Re24,906 (water-based and solvent-based adhesives), and U.S. Pat. No.4,833,179 (hot-melt adhesives), the disclosures of which are allincorporated herein by reference.

In a preferred embodiment, the nonwoven sheet materials of the presentinvention are coated with a high-solids latex pressure-sensitiveadhesive that is moisture insensitive, while also displaying anexcellent balance of adhesive properties, such as high compliance, andhigh shear, without adhesive build. See e.g., copending and co-filedpatent application 07/829,899 filed on Feb. 3, 1992, Lu et al., assignedto the assignee of the present invention, the disclosure of which isherein incorporated by reference. The characteristics and advantages ofthe preferred pressure-sensitive adhesive derive, at least in part, fromthe presence of a polymerizable surfactant and a low molecular weighthydrophobic polymer in the latex formulation.

The preferred latex pressure-sensitive adhesives coated on the nonwovensheet materials of the present invention are produced by emulsifying amixture of water, acrylate and vinyl monomers, ionic copolymerizablesurfactant, optional chain transfer agent, optional crosslinker, andhydrophobic polymer. The emulsion is heated with agitation undernitrogen atmosphere, then treated with initiator in portions to maintaintemperature control. The reaction mixture is heated and agitated untilreaction is complete. The resulting acrylic latex can then be coatedaccording to a variety of conventional methods known by those skilled inthe art.

The acrylate monomer component of the latex pressure-sensitive adhesivepreferably comprises C₄ to C₁₂ alkyl ester acrylate monomers. Suitablealkyl ester acrylate monomers include, without limitation, n-butylacrylate, amyl acrylate, hexyl acrylate, isooctyl acrylate, 2-ethylhexylacrylate, isononyl acrylate, decyl acrylate, dodecyl acrylate, andmixtures thereof.

Furthermore, the vinyl monomers combined with the acrylate monomerspreferably comprises 1) vinyl esters including but not limited to vinylacetate, vinyl propionate, vinyl butyrate, and the like, 2) C₁ to C₄alkyl esters of (meth)acrylic acid (including but not limited to methylmethacrylate, methyl acrylate, ethyl acrylate, ethyl methacrylate,isobutyl methacrylate, and the like), 3) styrene, and mixtures thereof.

Examples of useful copolymerizable ionic surfactants in the preferredlatex pressure-sensitive adhesive include, but are not limited to, thosedescribed in WO 89/12618, incorporated by reference herein. Thesurfactants described therein have a hydrophobic portion containingalpha-beta ethylenic unsaturation, a hydrophilic portion containing apoly(alkyleneoxy) segment, and an ionic segment. The preferredcopolymerizable surfactant is MAZON SAM-211 surfactant (PPG Industries,Inc.; described as an ethylene polyalkoxy ammonium sulfate, wherein thenumber of alkoxy groups is between about 5 and about 25, with a typicalexample having about 15 to about 20 ethoxy groups).

The latex pressure-sensitive adhesive may optionally further comprise acrosslinking agent, including, without limitation, multifunctionalacrylates such as diacrylates, triacrylates, and tetraacrylates, such as1,6-hexanedioldiacrylate, poly(ethylene glycol)diacrylates,poly(butadine)diacrylates, polyurethane diacrylates, andtrimethylolpropane triacrylate; 4-acryloxybenzophenone; divinyl benzene;and mixtures thereof. Also, optional chain transfer agents, such ascarbon tetrabromide, mercaptans, alcohols, and mixtures thereof may beincluded.

As noted above, the preferred latex pressure-sensitive adhesive includesa low molecular weight hydrophobic polymer. The term "hydrophobicpolymer", as used herein, refers to a water insoluble polymer. Usefulhydrophobic polymers have an average molecular weight ranging from about400 to about 50,000, preferably about 500 to about 20,000, mostpreferably about 600 to about 10,000. Examples of useful low molecularweight noncopolymerizable hydrophobic polymers include, but are notlimited to, those selected from the group consisting of polystyreneresins such as Piccolastic™ A75, D125, and D150 available from HerculesChemicals; poly(methylmethacrylate) (PMMA) resin; polybutadiene;poly(alpha-methylstyrene); butadiene-styrene block copolymers; and rosinesters such as Foral™ 85 and 105, available from Hercules, and mixturesthereof.

Preferably, the adhesive coated tapes of the present invention alsoutilize a releasable liner that covers the adhesive layer, or a releasecoating, such as a low adhesion backsize (LAB), coated on thenonadhesive side of the tape, to facilitate the winding of the tape intoeasy to use rolls. Preferably, an LAB coating is applied to thenonadhesive side of the tape using conventional coating methods in thetextile industry.

It is preferred that the LAB comprise a water-based composition,however, solvent-based materials such as polyvinylcarbamate are alsouseful. Suitable components of the water-based LAB include, withoutlimitation, polyethylenes, fluorochemicals, acrylates, silicones, vinylcopolymers, and combinations of these polymers with other polymers. Forexample, acceptable LABs useful in the tapes of the present inventionare described in U.S. Pat. No. 4,728,571, the disclosure of which isherein incorporated by reference.

In an especially preferred embodiment, as described in U.S. Pat. No.4,973,513, the disclosure of which is herein incorporated by reference,a water-based LAB is applied to the nonwoven sheet material immediatelyafter the chemical binding agent is infused therein. In this regard,especially preferred LABs comprise the poly(dimethyl siloxane) and/oracrylate polymers described as Release Coatings 1-15 of the U.S. Pat.No. 4,973,513. After coating, the LAB and chemical binding agentsinfused into the nonwoven sheet materials are dried as described in theU.S. Pat. No. 4,973,513.

Properties and Advantages

Applicant has surprisingly invented nonwoven sheet materials, and tapesformed therefrom, comprised of essentially nonfracturable fibers thatcan be made readily tearable (i.e., fracturable) in the cross webdirection of the sheet or tape, and yet are conformable in use. Inaddition, these materials and tapes can also exhibit a number of otheradvantageous properties including, enhanced dry strength, comparable wetstrength, tearability in the web direction, and a uniformity of strengthin both the web direction and cross web direction. To date, no singleprior art tape has been able to provide these advantages.

Typically, nonwoven sheet materials or tapes must sacrifice certainproperties in favor of others. For example, to obtain a tape that istearable in the cross web direction (e.g., a category I tape), overalltape strength, and in particular, wet strength, must be compromised.Likewise, to obtain a tape with good dry and wet strength (e.g., acategory II tape), tearability, and often conformability, are lost.Thus, category I and II tapes are often limited in their application.Conversely, the nonwoven sheet materials and tapes of the presentinvention should find wide use throughout the health-care field, andanywhere else, where a strong, conformable, and readily tearable tape isrequired. Specifically, the nonwoven sheet materials and tapes of thepresent invention combine the wet and dry web direction tensile strengthadvantages of typical category II materials with the Hand (i.e.,conformability) and cross web direction tear advantages of typicalcategory I materials to provide materials with wide applicability in thehealth-care field, athletics, and other areas.

The particular tear characteristics of a nonwoven sheet material or tapeof the present invention is evaluated according to the test proceduresdetailed below in the Test Methods section. This method provides asubjective measurement of whether a particular sheet or tape hasexcellent, good, fair, poor, or none (i.e., will not tear) tearcharacteristics, both in the web direction and the cross web direction.

In order to fall within the scope of the present invention, a nonwovensheet material, or a tape made therefrom, must be readilyfinger-tearable in the cross web direction. As used herein, a nonwovensheet material is readily finger-tearable when it exhibits at least fairtearability in the cross web direction. However, it is preferred thatthe nonwoven sheet material or tape exhibit at least good tearability,most preferably, excellent tearability, in the cross web direction. Inaddition, in a preferred embodiment, the nonwoven sheet materials ortapes of the present invention are also readily finger-tearable (i.e.,exhibit "fair" tearability) in the web direction of the sheet or tape.Accordingly, the most preferred sheet materials and tapes of the presentinvention exhibit at least fair tear characteristics in both the webdirection and cross web direction.

While finger-tearability is an important characteristic of the nonwovensheet materials and tapes of the present invention, it should not beprovided at the expense of the conformability (i.e., Hand) of the sheetmaterials and tapes. Accordingly, for a nonwoven sheet material and/ortape to fall within the scope of the present invention, it must alsoexhibit a Hand measurement of less than 250 grams for about a 20 cm widesheet or tape. Preferably, the nonwoven sheet materials and/or tapes ofthe present invention exhibit a Hand measurement of less than 200 grams,most preferably less than 150 grams for about a 20 cm wide sheet ortape. When the Hand measurement exceeds 250 grams, the nonwoven sheetmaterials and/or tapes are generally too stiff to properly conform tothe skin or other surface when in use.

The finger-tearability and Hand measurements for the nonwoven sheetmaterials and tapes of the present invention are affected by theparticular pattern-embossing conditions used on these materials.Preferably, a square or linear cross web embossing pattern, aspreviously described, is used. When either of these patterns isemployed, the nonwoven sheet materials and tapes of the presentinvention are readily finger-tearable in the cross web direction, andexhibit acceptable Hand measurements. In particular, the nonwoven sheetmaterials and tapes exhibit an easy, straight, and clean tear along theembossed lines of the linear or square patterns. However, when suchmaterials are not pattern embossed, they become essentiallynon-tearable, or if torn, exhibit uneven tear and frayed edges.Similarly, when the entire surface area of the materials are hotcalendered, they also are rendered essentially non-tearable. Inaddition, even if some of these materials maintain finger-tearability,they generally exhibit such high Hand measurements as to be essentiallynon-conformable.

The nonwoven sheet materials and tapes of the present invention alsoexhibit enhanced web direction tensile strength values per weight offiber used in the fibrous web, that are comparable to those exhibited bytypical category II materials. This is especially true with respect tothe wet web direction tensile strength of these materials. Even thoughthese nonwoven sheet materials and tapes are readily finger-tearable inthe cross web direction, they still exhibit a web direction wet-breaktensile strength of at least about 10 N/cm, preferably at least about 15N/cm, and more preferably at least about 20 N/cm. Likewise, the webdirection dry-break tensile strength of these materials is also at leastabout 10 N/cm, preferably at least about 15 N/cm, and more preferably atleast about 20 N/cm. Thus, the nonwoven sheet materials and tapes of thepresent invention unexpectedly show no appreciable drop in web directiontensile strength when wet, as compared to dry. Conversely, typicalcategory I cellulosic fiber materials (e.g., cellulose acetate andrayon) exhibit a 30%-40% reduction in tensile strength when wet.Furthermore, the finger-tearability of the sheet materials and tapes ofthe present invention is in direct contrast to typical category IImaterials that are essentially non-tearable in either the web directionor cross web direction.

Preferably, the nonwoven sheet materials and tapes of the presentinvention also exhibit enhanced tensile strength in both the webdirection and cross web direction. In this regard, it is preferred thatthe ratio of web direction tensile strength to cross web directiontensile strength (i.e., WD:CD ratio) be less than 3:1, even morepreferably less than 2:1. Furthermore, these materials also preferablyexhibit a web direction dry elongation between about 15% to about 40%,more preferably from about 20% to about 30%.

Test Methods

The tear properties of the nonwoven sheet materials and tapes of thepresent invention are assessed by a test group of individuals who arefamiliar with such materials. Specifically, these individuals arefamiliar with medical tapes, athletic tapes, and the like, their uses,and application techniques.

Each test group comprises four individuals, who are supplied withexample nonwoven sheet materials and tapes for evaluation. The testgroup evaluates these materials and tapes for ease of tear in both theweb direction (i.e. downweb) and cross web direction (i.e. crossweb),tear initiation, straightness of the tear, smoothness of the torn edge,and the force required to complete the tear. Each of these tearcharacteristics are rated either excellent (4), good (3), fair (2), poor(1), or none (0) (i.e., the individual was unable to tear the material).The results reported by the four individuals comprising the test groupare then combined for each example material, averaged for the fourindividuals, rounded to the nearest value, and reported as one of theabove-noted tear characteristic values.

The tear characteristics of the nonwoven sheet materials was evaluatedusing 2.5 cm×30 cm or 5 cm×30 cm die cut samples, with the web directiontear characteristics being evaluated along the 30 cm length, and crossweb direction tear characteristics along the 2.5 cm or 5 cm length. Thetear characteristics of example tapes was evaluated on rolled tapehaving 2.5 cm or 5 cm widths, with the cross web direction tearcharacteristics being evaluated along the 2.5 cm or 5 cm length, whilethe web direction tear characteristics were evaluated along anapproximately 20 cm length of the downweb portion of the tape.

The total Hand measurement in grams of example nonwoven sheet materialsor tapes provides a measure of the drape/conformability of thesematerials. Those materials with a relatively high Hand value are stiffand nonconformable. Conversely, relatively low Hand values reflectssoft, conformable materials. The Hand values reported for the followingexamples were obtained on a Thwing-Albert Handle-o-Meter™ Model No.211-300 (Thwing-Albert Instrument Co., Philadelphia, Pa.), according tothe procedures outlined in the instruction manual included with ModelNo. 211-300, the disclosure of which is herein incorporated byreference. All of the Hand measurements were performed on about 20 cmsquare sheet materials.

The tensile properties of the example nonwoven sheet materials and tapesreported herein were measured using an Instron™ tensile tester (InstronCorp., Canton, Mass.). The web direction and cross web direction tensilestrength (i.e. dry break as reported in N/cm) and web directionelongation (percent) were measured in accordance with ASTM test methodD-1682-64. The web direction wet tensile strength (i.e. wet break asreported in N/cm) was also measured in accordance with ASTM test methodD-1682-64, after soaking the example materials for 5 minutes indeionized water maintained at 20° C. Thereafter, the test samples wereblotted dry and immediately tested. After obtaining the above-notedtensile strength measurements, the ratio of web direction to cross webdirection tensile strength (i.e. WD:CD) of the dry materials wascalculated.

The invention will be further illustrated by reference to the followingnon-limiting Examples. All parts and percentages are expressed as partsby weight unless otherwise indicated.

EXAMPLES 1-8, AND COMPARATIVE EXAMPLES 9-18

The nonwoven sheet materials of Example 1-8 and Comparative Examples9-18 were made on a Hergeth Random-Card machine (Hergeth-Hollingsworth,GMBH, Dulman, Germany), utilizing conventional nonwoven web formationtechniques. The fiber composition, total fiber weight, chemical binderweight, and pattern embossing conditions employed with each of theExample and Comparative Example sheet materials are shown in Tables 1and 3 below.

The nonwoven sheet materials of Examples 1-8, and Comparative Examples9-18 utilized either a 0.75 denier, 38 mm, type L-30 polyethyleneterephthalate (PET) staple fiber (Eastman Chemical Products, Inc.,Kingsport, Tenn.), or a 1.25 denier, 38 mm, type T-121 PET staple fiber(Hoechst Celanese Corp., Charlotte, N.C.). In addition, the sheetmaterials of Comparative Examples 9-13 utilized a 1.5 denier, 40 mm,standard viscose processed rayon staple fiber (Courtauld's NorthAmerica, Inc., New York, N.Y.) in conjunction with the above-noted PETstaple fibers.

Either a 1.5 denier, 38 mm, Diawa™ binder fiber (a core-sheath fibercontaining a crystalline polypropylene core, and a meltable polyethylenefiber sheath; Chori America, Inc., Los Angeles, Calif.), or a 2 denier,38 mm, type K-54 binder fiber (a core-sheath fiber an oriented polyestercore, and an amorphous, meltable polyester sheath; Hoechst CelaneseCorp., Charlotte, N.C.), were utilized to form the nonwoven sheetmaterials of Examples 1-8 and Comparative Examples 9-18.

All of the nonwoven sheet materials of Examples 1-8, and ComparativeExamples 10-14, and 18 were patterned embossed, or flat calendered,using the processing conditions listed in Tables 1 and 3 herein.Thereafter, the Example and Comparative Example sheet materials weresaturated with an acrylic vinyl acetate copolymer latex chemical binder(No. 78-6283, National Starch and Chemical Co., Bridgewater, N.J.; a 45%solids latex, diluted to 25%-35% solids with deionized water). Inaddition, a poly(dimethyl siloxane) containing low adhesion backsize(LAB), described as Coating 1 of U.S. Pat. No. 4,973,513, was coatedonto the sheet materials immediately after the chemical binder, usingthe method disclosed in the U.S. Pat. No. 4,973,513, after which thesheet materials were dried in an oven.

Various mechanical and tear properties of the nonwoven sheet materialsof Examples 1-8 and Comparative Examples 9-18 were determined accordingto the test methods described herein. The ratio of machine direction tocross machine direction tensile strength (MD:CD), machine direction drytensile strength (MD DRY BREAK), machine direction wet tensile strength(MD WET BREAK), machine direction percent elongation (MD DRY ELONG.),Hand, and tear characteristics in both the machine direction and crossmachine direction are reported in Tables 2 and 4 below.

                  TABLE 1                                                         ______________________________________                                        Fiber composition, total fiber weight, chemical binder                        weight, and pattern embossing conditions for the nonwoven                     sheet materials of Examples 1-8.                                                                Fiber    Binder                                                                              Emboss Emboss                                Ex.               Weight   Weight                                                                              Pattern                                                                              Condition                             No.   Fiber Comp. (g/m.sup.2)                                                                            (g/m.sup.2)                                                                         (%)    (°C./MPa)                      ______________________________________                                        1     10% 0.75d PET                                                                             21       22    square 135/0.24                                    30% 1.5d Diawa             (26%)                                        2     80% 0.75d PET                                                                             21       23    square 135/0.24                                    20% 1.5d Diawa             (26%)                                        3     90% 0.75d PET                                                                             21       28    square 135/0.24                                    10% 1.5d Diawa             (26%)                                        4     90% 0.75d PET                                                                             21       18    square 135/0.24                                    10% 1.5d Diawa             (26%)                                        5     80% 0.75d PET                                                                             22       19    square 135/0.24                                    20% 2.0d K-54              (26%)                                        6     80% 1.25d PET                                                                             21       21    square 160/0.28                                    20% 2.0d K-54              (26%)                                        7     80% 1.25d PET                                                                             21       20    square 132/0.19                                    20% 2.0d K-54              (26%)                                        8     80% 1.25d PET                                                                             21       21    square 135/0.24                                    20% 1.5d Diawa             (26%)                                        ______________________________________                                    

                  TABLE 2                                                         ______________________________________                                        Ratio of machine direction to cross machine direction                         tensile strength (MD:CD), machine direction dry tensile                       strength (MD DRY BREAK), machine direction wet tensile                        strength (MD WET BREAK), machine direction percent                            elongation (MD DRY ELONG.), Hand, and machine direction                       (MD) and cross machine direction (CD) tear                                    characteristics of the nonwoven sheet materials of Examples 1-8.                           MD Dry   MD Wet MD Dry                                           Ex.  MD:CD   Break    Break  Elong. Hand Tear                                 No.  Ratio   (N/cm)   (N/cm) (%)    (g)  MD   CD                              ______________________________________                                        1    1.5:1   14       14     22     62   fair good                            2    1.8:1   16       16     20     49   poor fair                            3    1.4:1   15       15     23     103  fair good                            4    1.6:1   13       13     20     38   fair good                            5    1.4:1   13       13     18     35   good good                            6    1.7:1   20       17     25     42   good good                            7    1.7:1   17       16     28     35   good good                            8    2.9:1   20       19     38     44   good good                            ______________________________________                                    

                  TABLE 3                                                         ______________________________________                                        Fiber composition, total fiber weight, chemical binder                        weight, and pattern embossing conditions for the nonwoven                     sheet materials of Comparative Examples 9-18.                                 CP.               Fiber    Binder                                                                              Emboss Emboss                                Ex.               Weight   Weight                                                                              Pattern                                                                              Condition                             No.   Fiber Comp. (g/m.sup.2)                                                                            (g/m.sup.2)                                                                         (%)    (°C./MPa)                      ______________________________________                                        9     50% 0.75d PET                                                                             21       22    none   na                                          30% 1.5d Rayon                                                                20% 1.5d Diawa                                                          10    50% 0.75d PET                                                                             21       22    linear 129/0.17                                    30% 1.5d Rayon              (15%)                                             20% 1.5d Diawa                                                          11    50% 0.75d PET                                                                             21       22    square 127/0.21                                    30% 1.5d Rayon              (26%)                                             20% 1.5d Diawa                                                          12    50% 0.75d PET                                                                             21       22    linear 129/0.24                                    30% 1.5d Rayon              (15%)                                             20% 1.5d Diawa                                                          13    50% 0.75d PET                                                                             20       22    flat@  127/0.17                                    30% 1.5d Rayon             (100%)                                             20% 1.5d Diawa                                                          14    70% 0.75d PET                                                                             22       22    flat@  135/0.24                                    30% 1.5d Diawa             (100%)                                       15    70% 0.75d PET                                                                             21       22    none   na                                          30% 1.5d Diawa                                                          16    80% 0.75d PET                                                                             21       24    none   na                                          20% 1.5d Diawa                                                          17    80% 1.25d PET                                                                             21       24    none   na                                          20% 2.0d K-54                                                           18    80% 1.25d PET                                                                             21       19    flat@  141/0.17                                    20% 2.0d K-54              (100%)                                       ______________________________________                                         @These comparative sheet materials were not pattern embossed, but were        flat calendered over essentially all (i.e., 100%) of their surface area. 

                  TABLE 4                                                         ______________________________________                                        Ratio of machine direction to cross machine direction                         tensile strength (MD:CD), machine direction dry tensile                       strength (MD DRY BREAK), machine direction wet tensile                        strength (MD WET BREAK), machine direction percent                            elongation (MD DRY ELONG.), Hand, and machine direction                       (MD) and cross machine direction (CD) tear                                    characteristics of the nonwoven sheet materials of                            Comparative Examples 9-18.                                                    Cp.          MD Dry   MD Wet MD Dry                                           Ex.  MD:CD   Break    Break  Elong. Hand Tear                                 No.  Ratio   (N/cm)   (N/cm) (%)    (g)  MD   CD                              ______________________________________                                        9    1.2:1   12       8      23     66   poor fair                            10   1.3:1   9        6      23     58   poor good                            11   1.5:1   9        6      17     38   good good                            12   1.1:1   6        4      17     43   poor good                            13   1.2:1   11       8      14     130  fair fair                            14   1.6:1   15       15     19     167  poor none                            15   1.5:1   15       15     23     71   none none                            16   1.4:1   15       15     23     56   poor none                            17   2.2:1   19       18     42     38   none none                            18   1.8:1   21       21     20     87   poor poor                            ______________________________________                                    

A comparison of Tables 2 and 4 shows a marked difference in wet machinedirection tensile strength between the nonwoven sheet materials of thepresent invention and comparative materials incorporating the cellulosicfibers (e.g., rayon) typically found in category I materials.Specifically, the nonwoven sheet materials of Examples 1-8 exhibitmachine direction wet-break values between 13-19 N/cm, while the rayoncontaining materials of Comparative Examples 9-13 exhibit values between4-8 N/cm, i.e., an average of 58% lower wet strength than the sheetmaterials of the present invention. Similarly, the machine directiondry-break values for the materials of Comparative Examples 9-13 are alsosubstantially lower than those of the nonwoven sheet materials ofExamples 1-8 (i.e., 6-12 N/cm versus 13-20 N/cm, respectively).

In addition, the poor or none cross machine direction tearcharacteristics of Comparative Examples 14-18 show that, even when fibercompositions analogous to those used in the nonwoven sheet materials ofthe present invention are employed, failure to pattern emboss the sheetmaterials, or complete flat calendering of the sheet materials, rendersthem essentially non-tearable. Furthermore, the comparative materialsare also essentially non-tearable along the machine direction of thesheet. In contrast, the square embossing pattern used on the nonwovensheet materials yields materials that are all finger-tearable in thecross machine direction, and substantially all finger-tearable in themachine direction. Further, it is believed that the poor machinedirection tear characteristics of the Example 2 sheet material resultedfrom poor processing conditions. Specifically, the sheet material ofExample 2 was formed at a 30% faster line speed than the other examplematerials. This variation in line speed would be expected to reduce theeffectiveness of the thermal bonding resulting from pattern embossing,and thereby result in poorer tear properties.

EXAMPLES 19-22, AND COMPARATIVE EXAMPLES 23-34

The fibrous webs of the nonwoven sheet materials of Example 19-22 andComparative Examples 23-34 were made by Veratec, Inc., of Walpole,Mass., on their proprietary process lines. The fibrous nonwoven webswere both randomly carded and hydroentangled prior to receipt byApplicant. Thereafter, the webs were further processed by Applicant toarrive at the Example and Comparative Example nonwoven sheet materials.The fiber composition, total fiber weight, chemical binder weight, andpattern embossing conditions employed with each of the Example andComparative Example sheet materials are shown in Tables 5 and 7 below.

The nonwoven sheet materials of Examples 19-22, and Comparative Examples23-34, utilized either a 0.75 denier, 38 mm, standard polyethyleneterephthalate (PET) staple fiber, or a 1.2 denier, 38 mm, standard PETstaple fiber (Hoechst Celanese Corp., Charlotte, N.C.). In addition, thesheet materials of Comparative Examples 23-26 utilized a 1.5 denier, 40mm, standard viscose processed rayon staple fiber (Courtauld's NorthAmerica, Inc., New York, N.Y.) in conjunction with the above-notedpolyester staple fibers.

Either a 2 denier, 38 mm, Melty™ binder fiber (a core-sheath fibercontaining an oriented polyester core, and a meltable polyester fibersheath; Chori America, Inc., Los Angeles, Calif.), or a 2 denier, 38 mm,type K-52 binder fiber (a core-sheath fiber an oriented polyester core,and an amorphous, meltable polyester sheath; Hoechst Celanese Corp.,Charlotte, N.C.), were utilized to form the nonwoven sheet materials ofExamples 19-22 and Comparative Examples 23-34.

All of the sheet materials of Examples 19-22, and Comparative Examples26, 30, and 32 were patterned embossed, or flat calendered, using theprocessing conditions listed in Tables 5 and 7 herein. Thereafter thehydroentangled and embossed sheet materials of Examples 19-22 andComparative Examples 23-27, 29-30, 32 and 34 were saturated with anacrylic vinyl acetate copolymer latex chemical binder (No. 78-6283,National Starch and Chemical Co., Bridgewater, N.J.; a 45% solids latex,diluted to 25%-35% solids with deionized water). However, the nonwovensheet materials of Comparative Examples 28, 31 and 33 were not saturatedwith any chemical binder. In addition, a poly(dimethylsiloxane)-containing LAB (i.e., Coating 1 of U.S. Pat. No. 4,973,513)was coated onto all the Example and Comparative Example sheet materialsimmediately after the chemical binder, using the method disclosed in theU.S. Pat. No. 4,973,513, after which, the sheet materials were dried inan oven.

Various mechanical and tear properties of the nonwoven sheet materialsof Examples 19-22 and Comparative Examples 23-34 were determinedaccording to the test methods described herein. The ratio of machinedirection to cross machine direction tensile strength (MD:CD), machinedirection dry tensile strength (MD DRY BREAK), machine direction wettensile strength (MD WET BREAK), machine direction percent elongation(MD DRY ELONG.), Hand, and tear characteristics in both the machinedirection and cross machine direction are reported in Tables 6 and 8below.

                  TABLE 5                                                         ______________________________________                                        Fiber composition, total fiber weight, chemical binder                        weight, and pattern embossing conditions for the nonwoven                     sheet materials of Comparative Examples 19-22.                                                  Fiber    Binder                                                                              Emboss Emboss                                Ex.               Weight   Weight                                                                              Pattern                                                                              Condition                             No.   Fiber Comp. (g/m.sup.2)                                                                            (g/m.sup.2)                                                                         (%)    (°C./MPa)                      ______________________________________                                        19    90% 1.0d PET                                                                              39       21    square 129/0.19                                    10% 2.0d Melty             (26%)                                        20    85% 0.75d PET                                                                             46       20    square 135/0.18                                    15% 2.0d K-52              (26%)                                        21    80% 1.0d PET                                                                              46       19    square 141/0.18                                    20% 1.5d K-52              (26%)                                        22    80% 1.0d PET                                                                              44       18    square 141/0.15                                    20% 2.0d K-52              (26%)                                        ______________________________________                                    

                  TABLE 6                                                         ______________________________________                                        Ratio of machine direction to cross machine direction                         tensile strength (MD:CD), machine direction dry tensile                       strength (MD DRY BREAK), machine direction wet tensile                        strength (MD WET BREAK), machine direction percent                            elongation (MD DRY ELONG.), Hand, and machine direction                       (MD) and cross machine direction (CD) tear                                    characteristics of the nonwoven sheet materials of                            Examples 19-22.                                                                            MD Dry   MD Wet MD Dry                                           Ex.  MD:CD   Break    Break  Elong. Hand Tear                                 No.  Ratio   (N/cm)   (N/cm) (%)    (g)  MD   CD                              ______________________________________                                        19   1.4:1   25       24     17     105  good exce                            20   2.3:1   34       34     17     135  good good                            21   2.9:1   37       37     22     120  good good                            22   2.4:1   35       33     19     105  good exce                            ______________________________________                                    

                  TABLE 7                                                         ______________________________________                                        Fiber composition, total fiber weight, chemical binder                        weight, and pattern embossing conditions for the nonwoven                     sheet materials of Comparative Examples 23-34.                                Cp.               Fiber    Binder                                                                              Emboss Emboss                                Ex.               Weight   Weight                                                                              Pattern                                                                              Condition                             No.   Fiber Comp. (g/m.sup.2)                                                                            (g/m.sup.2)                                                                         (%)    (°C./MPa)                      ______________________________________                                        23    85% 1.5d Rayon                                                                            45       21    none   na                                          15% 0.75d PET                                                           24    75% 1.5d Rayon                                                                            44       19    none   na                                          25% 0.75d PET                                                           25    60% 1.5d Rayon                                                                            44       19    none   na                                          25% 0.75d PET                                                                 15% 2.0d K-52                                                           26    60% 1.5d Rayon                                                                            44       19    cross  141/0.19                                    25% 0.75d PET               (15%)                                             15% 2.0d K-52                                                           27    90% 1.0d PET                                                                              39       21    none   na                                          10% 2.0d Melty                                                          28    85% 0.75d PET                                                                             46       none  none   na                                          15% 2.0d K-52                                                           29    85% 0.75d PET                                                                             46       22    none   na                                          15% 2.0d K-52                                                           30    85% 0.75d PET                                                                             46       19    flat@  135/0.18                                    15% 2.0d K-52              (100%)                                       31    80% 1.0d PET                                                                              46       none  none   na                                          20% 2.0d K-52                                                           32    80% 1.0d PET                                                                              46       17    flat@  141/0.18                                    20% 1.5d K-52              (100%)                                       33    80% 1.3d PET                                                                              44       none  none   na                                          20% 2.0d K-52                                                           34    80% 1.3d PET                                                                              44       23    none   na                                          20% 2.0d K-52                                                           ______________________________________                                         @These comparative sheet materials were not pattern embossed, but were        flat calendered over essentially all (i.e., 100%) of their surface area. 

                  TABLE 8                                                         ______________________________________                                        Ratio of machine direction to cross machine direction                         tensile strength (MD:CD), machine direction dry tensile                       strength (MD DRY BREAK), machine direction wet tensile                        strength (MD WET BREAK), machine direction percent                            elongation (MD DRY ELONG.), Hand, and machine direction                       (MD) and cross machine direction (CD) tear                                    characteristics of the nonwoven sheet materials of Examples 23-34.            CP.          MD Dry   MD Wet MD Dry                                           Ex.  MD:CD   Break    Break  Elong. Hand Tear                                 No.  Ratio   (N/cm)   (N/cm) (%)    (g)  MD   CD                              ______________________________________                                        23   2.2:1   27       12     18     240  poor fair                            24   2.0:1   22       13     20     305  poor fair                            25   2.1:1   30       16     29     260  poor fair                            26   2.1:1   26       16     19     125  poor fair                            27   1.9:1   25       24     17     140  poor poor                            28   2.3:1   30       0.4    37     85   poor none                            29   2.3:1   39       38     20     360  poor poor                            30   2.3:1   46       45     13     670  fair fair                            31   2.9:1   39       40     42     75   none none                            32   2.9:1   45       44     15     740  poor poor                            33   2.4:1   34       33     46     70   none none                            34   2.4:1   39       43     26     290  poor poor                            ______________________________________                                    

A comparison of the values reported in Tables 6 and 8 shows essentiallythe same results as described for the nonwoven sheet materials ofExamples 1-8 (Table 2) and Comparative Examples 9-18 (Table 4). Therayon-containing sheet materials of Comparative Examples 23-26 all showsubstantially lower machine direction wet-break values (i.e., 12-16N/cm) than those of Example sheet materials 19-22 (i.e., 24-37 N/cm). Inaddition, there is also a readily apparent difference between themachine direction dry-break values between the Example and ComparativeExample materials (25-37 N/cm for Examples 19-22; 22-30 N/cm forComparative Examples 23-26). In this regard, it should also be notedthat the wet and dry machine direction tensile strength of theComparative Example materials fall substantially below those of theExample materials, when cellulosic rayon fibers are used as the solestaple fiber of the web (i.e., Comparative Examples 23-24), or whenrayon fibers are used in combination with tensilized non-fracturablestable fibers (i.e., Comparative Examples 25-26) of the type that areemployed in the nonwoven sheet materials of the present invention.

Likewise, with the exception of Comparative Example 30, the similarfiber composition materials of Comparative Examples 27-29, and 31-34 areall essentially non-tearable in the cross machine direction. Incontrast, the nonwoven sheet materials of Examples 19-22 all show goodto excellent tearability in both the cross machine direction and machinedirection. Even though the nonwoven sheet material of ComparativeExample 30 exhibits fair tearability in both the cross machine directionand machine direction, it also exhibits a Hand measurement of 670 grams,making it so stiff as to be not useable as a conformable sheet material.Similarly, Comparative Example materials 24, 25, 29, 32, and 34 alsoexhibit Hand values exceeding those required of the nonwoven sheetmaterials of the present invention. In contrast, the nonwoven sheetmaterials of Examples 19-22 all exhibit Hand values of between 105-135grams.

EXAMPLES 35-42, AND COMPARATIVE EXAMPLES 43-52

Example tapes 35-42, and Comparative Example tapes 43-52 use thenonwoven sheet materials of Examples 1-8, and Comparative Examples 9-18,respectively, as the backing materials for the tape constructions (SeeTables 1 and 3). After pattern embossing, application of the chemicalbinder and LAB (per U.S. Pat. No. 4,973,513), and drying of thesematerials, a high-solids latex, acrylate-based pressure sensitiveadhesive (PSA) (i.e., Example 5 of copending and co-filed U.S. patentapplication Attorney Docket No. 48167USA6A) was applied to thenon-LAB-coated side of the nonwoven backing according to the proceduresoutlined in U.S. Pat. No. 3,121,021.

Various mechanical and tear properties of the tapes of Examples 35-42and Comparative Examples 43-52 were determined according to the testmethods described herein. Specifically, the machine direction drytensile strength (MD DRY BREAK), machine direction percent elongation(MD DRY ELONG.), and tear characteristics in both the machine directionand cross machine direction are reported in Tables 9 and 10 below. Inaddition, Tables 9 and 10 also report the ratio of machine direction tocross machine direction tensile strength (MD:CD), the machine directionwet tensile strength (MD WET BREAK), and Hand of the Example andComparative Example nonwoven sheet materials comprising the tapebackings (See Tables 2 and 4 herein). The reported values for theseproperties remain essentially unchanged when a pressure-sensitiveadhesive is applied to the nonwoven sheet materials to form the Exampleand Comparative Example tapes described herein.

                  TABLE 9                                                         ______________________________________                                        Ratio of machine direction to cross machine direction                         tensile strength (MD:CD), machine direction dry tensile                       strength (MD DRY BREAK), machine direction wet tensile                        strength (MD WET BREAK), machine direction percent                            elongation (MD DRY ELONG.), Hand, and machine direction                       (MD) and cross machine direction (CD) tear                                    characteristics of the tapes of Examples 35-42.                                            MD Dry   MD Wet MD Dry                                           Ex.  MD:CD   Break    Break  Elong. Hand Tear                                 No.  Ratio   (N/cm)   (N/cm) (%)    (g)  MD   CD                              ______________________________________                                        35   1.5:1   16       14     22     62   fair good                            36   1.8:1   17       16     21     49   poor fair                            37   1.4:1   16       15     23     103  fair good                            38   1.6:1   14       13     23     38   fair good                            39   1.4:1   14       13     19     35   good good                            40   1.7:1   21       17     23     42   good exec                            41   1.7:1   17       16     27     35   good good                            42   2.9:1   20       19     31     44   good good                            ______________________________________                                    

                  TABLE 10                                                        ______________________________________                                        Ratio of machine direction to cross direction tensile                         strength (MD:CD), machine direction dry tensile strength                      (MD DRY BREAK), machine direction wet tensile strength                        (MD WET BREAK), machine direction percent elongation (MD                      DRY ELONG.), Hand, and machine direction (MD) and cross                       direction (CD) tear characteristics of the tapes of                           Comparative Examples 43-52.                                                   CP.          MD Dry   MD Wet MD Dry                                           Ex.  MD:CD   Break    Break  Elong. Hand Tear                                 No.  Ratio   (N/cm)   (N/cm) (%)    (g)  MD   CD                              ______________________________________                                        43   1.2:1   12       8      23     66   poor fair                            44   1.3:1   9        6      23     58   poor good                            45   1.5:1   9        6      17     38   good good                            46   1.1:1   6        4      17     43   poor good                            47   1.2:1   12       8      15     130  fair fair                            48   1.6:1   17       15     20     167  fair none                            49   1.5:1   17       15     23     71   none none                            50   1.4:1   16       15     22     56   poor none                            51   2.2:1   20       18     34     38   none none                            52   1.8:1   20       21     20     87   poor poor                            ______________________________________                                    

EXAMPLES 53-56, AND COMPARATIVE EXAMPLES 57-68

Example tapes 53-56, and Comparative Example tapes 57-68 used thenonwoven sheet materials of Examples 19-22 and Comparative Examples23-34, respectively as the backing materials for the tape constructions(See Tables 5 and 7). Also, these Example and Comparative Example tapesused the same LAB and PSA adhesive coatings, as described for Examples35-42 and Comparative Examples 43-52 herein.

Various mechanical and tear properties of the tapes of Examples 53-56and Comparative Examples 57-68 were determined according to the testmethods described herein. The machine direction dry tensile strength (MDDRY BREAK), machine direction percent elongation (MD DRY ELONG.), andtear characteristics in both the machine direction and cross machinedirection are reported in Tables 11 and 12 below. In addition, Tables 11and 12 also report the ratio of machine direction to cross machinedirection tensile strength (MD:CD), machine direction wet tensilestrength (MD WET BREAK), and Hand of the Example and Comparative Examplesheet materials comprising the tape backings (See Tables 6 and 8herein). As noted in Examples 35-42 and Comparative Examples 43-52,these values are essentially unchanged between the nonwoven sheetmaterials and resulting tapes coated with a pressure-sensitive adhesive.

                  TABLE 11                                                        ______________________________________                                        Ratio of machine direction to cross direction tensile                         strength (MD:CD), machine direction dry tensile strength                      (MD DRY BREAK), machine direction wet tensile strength                        (MD WET BREAK), machine direction percent elongation (MD                      DRY ELONG.), Hand, and machine direction (MD) and cross                       direction (CD) tear characteristics of the tapes of                           Examples 53-56.                                                                            MD Dry   MD Wet MD Dry                                           Ex.  MD:CD   Break    Break  Elong. Hand Tear                                 No.  Ratio   (N/cm)   (N/cm) (%)    (g)  MD   CD                              ______________________________________                                        53   1.4:1   25       24     17     105  good exce                            54   2.3:1   37       34     16     135  good good                            55   2.9:1   39       37     21     120  good good                            56   2.4:1   35       33     18     105  good exce                            ______________________________________                                    

                  TABLE 12                                                        ______________________________________                                        Ratio of machine direction to cross machine direction                         tensile strength (MD:CD), machine direction dry tensile                       strength (MD DRY BREAK), machine direction wet tensile                        strength (MD WET BREAK), machine direction percent                            elongation (MD DRY ELONG.), Hand, and machine direction                       (MD) and cross machine direction (CD) tear                                    characteristics of the tapes of Comparative Examples 57-68.                   CP.          MD Dry   MD Wet MD Dry                                           Ex.  MD:CD   Break    Break  Elong. Hand Tear                                 No.  Ratio   (N/cm)   (N/cm) (%)    (g)  MD   CD                              ______________________________________                                        57   2.2:1   29       12     17     240  poor fair                            58   2.0:1   23       13     19     305  poor fair                            59   2.1:1   26       16     19     260  poor fair                            60   2.1:1   26       16     19     125  poor fair                            61   1.9:1   nd       24     nd     140  poor poor                            62   2.3:1   nd       0.4    nd      85  nd   nd                              63   2.3:1   nd       38     nd     360  nd   nd                              64   2.3:1   47       45     12     670  fair fair                            65   2.9:1   41       40     41      75  none none                            66   2.9:1   nd       44     nd     740  nd   nd                              67   2.4:1   35       33     45      70  none none                            68   2.4:1   39       43     25     290  poor fair                            ______________________________________                                         nd = parameter values not determined for these Comparative Example            materials.                                                               

The values reported in Tables 9-12 all demonstrate that application of apressure-sensitive adhesive coating to the nonwoven sheet materials ofExamples 1-8, and 19-22, and Comparative Examples 9-18, and 23-34, donot, in any significant way, change the properties reported for thesematerials. In this regard, all of the previously discussed advantages ofthe nonwoven sheet materials of the present invention apply equally wellto tapes formed therefrom. Thus, the adhesive tapes of the presentinvention exhibit substantially higher machine direction dry and wettensile strength (See Tables 9 and 11) than the rayon-containing tapesof Comparative Examples 43-47, and 57-60 (Tables 10 and 12). Also, theseExamples are finger-tearable in the cross machine direction and machinedirection, while those of Comparative Example tapes 48-52, 61-63, and65-67 are not. Further, those Comparatives tapes that do exhibit fairtearability, also exhibit large Hand values outside of those provided bythe tapes of the present invention.

EXAMPLES 77 AND 78, AND COMPARATIVE EXAMPLES 69-76

Examples 77 and 78 and Comparative Examples 69-76 demonstrate that theprocessing order of the present invention is important to preparenonwoven sheet materials which are hand-tearable in the cross machinedirection. Examples 77 and 78 were prepared according to the presentinvention, i.e., first pattern embossed in a manner to impart handtearability in the cross web direction and then saturated with achemical binder. This is more fully described below. ComparativeExamples 69-76 were either prepared according to the processing order ofU.S. Pat. No. 4,292,360, i.e., first saturating with a chemical binderand then pattern embossing or were prepared by first flat calendering orembossing in a manner that did not impart hand tearability in the crossweb direction and then chemically binding.

The nonwoven sheet materials of Example 77 and 78 and ComparativeExamples 69-76 were made on a Hergeth Random-Card web(Hergeth-Hollingsworth, GMBH, Dulman, Germany), utilizing conventionalnonwoven web formation techniques. The fiber composition, total fiberweight, chemical binder weight, and pattern embossing conditionsemployed with each of the Example and Comparative Example sheetmaterials are shown in Table 13 below.

The nonwoven sheet materials of Examples 77 and 78, and ComparativeExamples 69-76 utilized a 1.2 denier, 38 mm, type L-67 PET staple fiber(Hoechst Celanese Corp., Charlotte, N.C.). In addition, the sheetmaterials of Comparative Examples 73 and 74 utilized a 1.5 denier, 40mm, standard viscose processed rayon staple fiber (Courtauld's NorthAmerica, Inc., New York, N.Y.) in conjunction with the above-noted PETstaple fibers.

A 2 denier, 38 mm, type K-54 binder fiber (a core-sheath fiber anoriented polyester core, and an amorphous, meltable polyester sheath;Hoechst Celanese Corp., Charlotte, N.C.), was utilized to form thenonwoven sheet materials of Examples 77 and 78 and Comparative Examples69-76.

Comparative Examples 72 and 74 were first saturated with an acrylicvinyl acetate copolymer latex chemical binder (No. 78-6283, availablefrom National Starch and Chemical Co., Bridgewater, N.J.; a 45% solidslatex, diluted to 25-35% solids with deionized water). These sampleswere saturated with a binder before embossing occurred and followed theprocessing order of procedures disclosed in U.S. Pat. No. 4,292,360.

The nonwoven sheet materials of Comparative Examples 70, 72 74-76 andExamples 77 and 78 were patterned embossed, or flat calendered, usingthe processing conditions listed in Table 13 herein.

Thereafter, the Example 76 and 77 and Comparative Examples 69-71, 73 and75 sheet materials were saturated with an acrylic vinyl acetatecopolymer latex chemical binder. Example 77 was saturated with chemicalbinder No. 78-6283 identified above. Comparative Examples 71-73 and 74were saturated with chemical binder No. 4260 available from NationalStarch and Chemical Co.; a 45% solids latex was diluted to 25-35% solidswith deionized water. For Example 76, chemical binder No. 1019 availablefrom Rohm & Haas was used; a 50% solids latex was diluted to 25-35%solids with deionized water.

Various mechanical and tear properties of the nonwoven sheet materialsof Examples 77 and 78 and Comparative Examples 69-76 were determinedaccording to the test methods described herein. The ratio of webdirection to cross web direction tensile strength (WD:CD), web directiondry tensile strength (WD DRY BREAK), web direction wet tensile strength(WD WET BREAK), web direction percent elongation (WD DRY ELONG.), Hand,and tear characteristics in both the web direction and cross webdirection are reported in Table 14 below.

                  TABLE 13                                                        ______________________________________                                        Fiber composition, total fiber weight, chemical binder                        weight, and pattern embossing conditions for the                              nonwoven sheet materials of Comparative Examples 69-76                        and Comparative Examples 77 and 78.                                           Ex./                                                                          C.P.              Fiber    Binder                                                                              Emboss Emboss                                Ex.               Weight   Weight                                                                              Pattern                                                                              Condition                             No.   Fiber Comp. (g/m.sup.2)                                                                            (g/m.sup.2)                                                                         (%)    (°C./MPa)                      ______________________________________                                        69    80% 1.2d PET                                                                              22       --    --     --                                          20% 2.0d K-54                                                           70    80% 1.2d PET                                                                              22       --    Square 130/0.28                                    20% 2.0d K-54               26%                                         71    80% 1.2d PET                                                                              21       23    --     --                                          20% 2.0d K-54                                                           72    80% 1.2d PET                                                                              21       23    Square 135/0.28                                    20% 2.0d K-54               26%                                               First saturated                                                               with binder,                                                                  then embossed                                                           73    40% 1.5d Rayon                                                                            23       24    --     --                                          40% 1.2d PET                                                                  20% 2.0d K-54                                                           74    40% 1.2d Rayon                                                                            23       24    Square 132/0.29                                    40% 1.2d PET                26%                                               20% 2.0d K-54                                                                 First saturated                                                               with binder,                                                                  then embossed                                                           75    70% 1.2d PET                                                                              40       --    Flat   136/0.30                                    30% 2.0d K-54              100%                                         76    70% 1.2d PET                                                                              40       36    Flat   136/0.30                                    30% 2.0d K-54              100%                                               First flat                                                                    calendered, then                                                              saturated with                                                                binder                                                                  77    80% 1.2d PET                                                                              31       63    Linear 134/0.30                                    20% 2.0d K-54               15%                                               First embossed,                                                               then saturated                                                                with binder                                                             78    80% 1.2d PET                                                                              22       21    Square 132/0.28                                    20% 2.0d K-54               26%                                               First embossed,                                                               then saturated                                                                with binder                                                             ______________________________________                                    

                  TABLE 14                                                        ______________________________________                                        Ratio of web direction to cross web direction tensile                         strength (WD:CD), web direction dry tensile strength                          (WD DRY BREAK), web direction wet tensile strength (WD                        WET BREAK), web direction percent elongation (WD DRY                          ELONG), Hand, and web direction (WD) and cross web                            direction (CD) tear characteristics of the nonwoven                           sheet materials of Comparative Examples 69-76 and                             Examples 77 and 78                                                                         WD Dry   MD Wet MD Dry                                           Ex.  WD:CD   Break    Break  Elong. Hand Tear                                 No.  Ratio   (N/cm)   (N/cm) (%)    (g)  WD   CD                              ______________________________________                                        69   *       *        *      *      *    *    *                               70   4.0:1   5        3      14     17   Poor Fair                            71   2.8:1   18       17     28     67   Fair Poor                            72   2.8:1   19       17     21     106  Fair Poor                            73   2.8:1   22       12     20     85   Good Poor                            74   2.8:1   22       12     20     88   Good Poor                            75   2.6:1   20       18     16     177  Fair Poor                            76   1.9:1   50       47     20     73   Good Fair                            77   2.5:1   40       38     21     75   Poor Good                            78   2.9:1   20       19     31     35   Good Good                            ______________________________________                                         *Too low to measure                                                      

Example 78 exhibited good tear in the cross web direction as compared toComparative Examples 72 and 74 which exhibited poor tear in the crossweb direction. Comparative Examples 72 and 74 were pattern embossed inthe same pattern as Example 78 but Comparative Examples 72 and 74 weresaturated with a chemical binder before embossing occurred, i.e.,according to the processing order disclosed in U.S. Pat. No. 4,292,360.Comparative Example 69 was not embossed or saturated with a chemicalbinder and therefore did not exhibit good tear properties. ComparativeExample 70 was only embossed in a square pattern and was not chemicallybonded and therefore did not exhibit good tear properties. ComparativeExample 71 was saturated with a binder but was not pattern embossed andtherefore did not tear well in either direction. Comparative Example 73included rayon fibers and was not pattern embossed and failed to tearwell in the cross web direction. Comparative Example 75 was flatcalendered instead of pattern embossed and was not saturated with achemical binder and therefore did not tear in the cross web direction.Comparative Example 76 was flat calendered and then saturated with abinder. Since the flat calendering did not pattern emboss the sample toimpart hand tearability, the sample did not tear well in the cross webdirection. Examples 77 and 78 were first pattern embossed to impart handtearability and then saturated with a chemical binder according to theprocess of the present invention. Both Examples 77 and 78 had good tearin the cross web direction. Example 77 was only embossed with a linearpattern which allowed for good tear in the cross web direction (thedirection of the lines) but poor tear in the web direction (across thelinear embossing).

While in accordance with the patent statutes, description of thepreferred weight fractions, processing conditions, and product usageshave been provided, the scope of the invention is not to be limitedthereto or thereby. Various modifications and alterations of the presentinvention will be apparent to those skilled in the art without departingfrom the scope and spirit of the present invention. The Examplesdescribed in this application are illustrative of the possibilities ofvarying the type, quantity, and ratio of fiber composition, as well aspattern embossing conditions to achieve properties for specificpurposes.

Consequently, for an understanding of the scope of the presentinvention, reference is made to the following claims.

What is claimed is:
 1. A method of making a nonwoven sheet materialcomprising:(a) forming a randomly interlaced fibrous web of tensilizednonfracturable staple fibers and binder fibers; (b) first patternembossing the fibrous web so as to be readily finger-tearable in thecross web direction; and (c) subsequent to pattern embossing, uniformlyinterbonding the fibrous web throughout using a chemical bonding agent,wherein the nonwoven sheet material exhibits a Hand measurement of lessthan 250 grams for about a 20 cm square sheet, and is readilyfinger-tearable in the cross web direction.
 2. A method of making anonwoven sheet material according to claim 1, wherein the patternembossing step comprises embossing a square pattern or a linear crossweb direction pattern onto the fibrous web.
 3. A method of making anonwoven sheet material according to claim 1, wherein the interbondingstep includes infusing the fibrous web with a water-based chemicalbinding agent.
 4. A method of making a nonwoven sheet material accordingto claim 3, further comprising, drying the fibrous web infused with thewater-based chemical binding agent until substantially all of the wateris removed.
 5. A method of making a nonwoven sheet material according toclaim 1, wherein the interbonding step comprises hydroentangling thefibrous web before pattern embossing of the fibrous web.
 6. A method ofmaking a nonwoven sheet material according to claim 1, furthercomprising, coating a layer of pressure-sensitive adhesive on a firstsurface of the nonwoven sheet material.
 7. A method of making a nonwovensheet material according to claim 6, further comprising, applying a lowadhesion composition to a second surface of the nonwoven sheet material.8. A method of making a nonwoven sheet material according to claim 6,further comprising, covering the pressure-sensitive adhesive coatedfirst surface of the nonwoven sheet material with a releasable liner.